A train may move forward or backward by 1, 2 or 3 hexes along the
railroad tracks, but it may not move when the tracks are blocked.You order it like any other unit, by playing a Command Card. If the
train is across two sections, it may be ordered in either section.
An enemy unit may target a train. One hit is scored for each Grenade rolled on the train. Place a Battle Star token on the locomotive for each hit on the train.
On the second hit, place a second Battle Star. On the third hit, place a third
Battle Star and remove the wagon. On the fourth hit, the locomotive is removed.
When both sections of the train are removed, place the locomotive on an empty Victory Medal space.
A train may ignore the first flag rolled against it. When it retreats,
it moves back (opposite way the locomotive is facing) one hex along the tracks for each Flag rolled against it. If it cannot retreat, place one Battle Star on the locomotive for each hex it cannot retreat.

Supply Train - Reinforcements
A locomotive and wagon may carry infantry or armor
reinforcement troops. The units that are being carried
are indicated in the scenario. Carried units may not
battle. When the locomotive arrives at the station, the
units riding on the supply train are placed on the hexes
adjacent to the locomotive and wagon. Units may not
move or battle the turn they arrive at the station.Armored Train
An armored train contains an artillery figure on its wagon piece. It may move up to 3 hexes and still battle. Apply the artillery range and firepower regular rules. Use the other train rules above for movement and counting damages (four grenades to destroy the train).

I could be wrong on this, but I think that the empty train is ordered either with a section card or a card that orders any unit. Cards that specifically order infantry do not, in general, order a supply train with infantry on board (Infantry Assault, Move-Out). However, if you had no infantry units on the gameboard you could still order the train using the last line of these cards -

Quote:

If you do not command any infantry units,issue an order to 1 unit of your choice

From what I know of supply trains, there a unit all its own, just use the Terrain Pack rules regardless of whats inside.
Another point is, since a unit in a train cant attack, it makes sense it cant be used to order the train.

The train does not seem to be classified as either armor or infantry. If this is true, one would think that a train in a train station would therefore gain no terrain benefits (-2 armor; -1 infantry) if attacked there. Is this true?

The train does not seem to be classified as either armor or infantry. If this is true, one would think that a train in a train station would therefore gain no terrain benefits (-2 armor; -1 infantry) if attacked there. Is this true?

Regardless of what unit is on the train station hex infantry gets -1 die when they attack and armor gets -2.

The train does not seem to be classified as either armor or infantry. If this is true, one would think that a train in a train station would therefore gain no terrain benefits (-2 armor; -1 infantry) if attacked there. Is this true?

Regardless of what unit is on the train station hex infantry gets -1 die when they attack and armor gets -2.